Contact sulphuric-acid process



Patented Dec. 4, 1928.

UNITED -STATES 1,694,123 PATENT OFFIGE.

ALPHONS O. JAE-GER, 0F GRAFTON, PENNSYLVANIA, ASSIGNOR TO THE SELDENCOM- PANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE.

CONTACT SULPHURIC-ACID PROCESS,

No Drawing.

This invention relates to processes for the production of sulphuric acidand sulphur trioxide by the contact sulphuric acid process.

In the patents of Alphons O. Jacger and Johann A. Bertsch, No. 1,657,754, patented January 31, 1928, No. 1,657,753,, patented Jan. 31, 1928,and co-pending Serial No. 88,- 488, filed February 15, 1926, processesare described for the catalytic oxidation of sul phur dioxideby means ofzeolite catalysts, in which the catalytically effective element ischemically combined in non-exchangeable form in the zeolite itself. Theprocesses may use zeolites which are undiluted or those which arediluted with various relat-irely inert substances, such as kieselguhr,pumice, and other carriers, either in a finely divided state or in theform of imissive fragments. I have found that catalysts of greateffectiveness possessing substantally all of the advantages of thezeolite catalysts, described in the application and patents hereinabevementioned, can be obtained by introducing catalytically effectivediluent bodies into zeolites and other base exchange bodies which arenot themselves catalysts for-the contact sulphuric acid process. Thepresent invention possesses the advantage that it is not necessary tochemically combine the catalytically effective components in the zeolitestructure and it is, therefore, possible to exerc'se a wide margin ofchoice in the catalytic component used. Apparently, ,the physicalstructure of' the zeolite, coupled with its chemical characteristics, iseffective, whether the catalytically effective component is itselfchemically combined with the zeolite or merely associated therewith,preferably in a uniform and homogeneous manner. It is thus possible toutilize many valuable effective catalysts which could not beincorporated chemically in any zeolite. Thus, for example, I have foundthat many salts of vanadic acid, such as, for example, iron salts,silver salts, and the like, are extraordinarily effective catalysts whenused as diluent bodies for zeolites which are not themselvescatalytically effective. Inaddition to salts of vanadic acid, such asiron vanadate and silver vanadate, which are ,known to be faircatalysts, other salts of vanadic acid, such as copper, cobalt, nickel,uranium, titanium, manganese, chromium, aluminum, beryllium, zirconiumand cerium vanadates, which are not normally considered as cata-Application filed March 10, 1927. Serial No. 174,414.

lysts, when united with a base exchange body act as very effectivecatalysts. Not only, 'thercfore, does the present invention permit themore effective usage of known catalysts, but it also transforn'isvanadic acid salts which are not usable as catalysts into highlyeffective contact masses. Such salts of Vanadic acid cannot, of course,be catalytically combined with the zeolite, and, therefore, the fieltl.of available catalysts is greatly increased due to the fact that it isnot necessary to restrict oneself to products which can be chemicallyincorporated in a zeolite or other base exchange body. I am not sure whythe zeolites, which are themselves not catalysts or at any rate noteficctive catalysts, can transform such catalysts as, for example, saltsof ranadic acid, into contact masses of extraordinary activity. I wasformcrlyof the opinion that it was necessary to chemically combine thecatalytically effective component with the zeolite itself, and thisopinion is expressed in the joint application, and patents, abovereferred to. Whether or not this may be the reason for the catalyticefficiency of the zeolites there described, is not definitely proven,but I am of the opinion that this factor is not the only one and perhapsnot the most important one in determining whether or not aparticularzeolite complex is an efficient catalyst. I am now of theopinion that the physical structure of the zeolite is perhaps ofgreaterimportance thanthe chemical combination of the zeolite with thecatalytic elements. It seems probable, however, that the zeolite doesnot act purely as a microporous inert carrier, since other carriers ofcomparable porosity do not possess all of the advantages of zeolites. Iam, therefore, of the opinion that the zeolite also acts as a chemicalactivator of the catalyst, although not chemically 'combined therewith.I believe that the high molecular silicic acid complex of the zeoliteconstitutes an important chemical activator or promoter, which enhancesthe activity of the catalyst embedded therein, apart from its physicalcharacteristics. The above explanations are not in any sense intended tolimit the invention, but merely constitute the best explanation which Iknow at the present time to account for the remarkable effectiveness ofthe catalysts wh ch arepreparcd according to the present invention, aneffectiveness which far exceeds the sum of the catalytic effectivenessof the zeolite itself and the catalyst embedded therein.

In the following specification and claims, a sharp distinction will bedrawn between substances which are actual practical cat-alysts forcontact sulphuric acid and other substances, which, while they may havea certain amount of catalytic activity, are nevertheles incapable bythemselves of acting as catalysts giving commercially satisfactoryyields. Thus, for example, certain iron zeolites may be used for thecatalytic oxidation of sulphur dioxide. but cannot be used practicallyasthe yields run but little above 50 or 60%. In the present application,therefore, an effective catalyst W111 be defined as one which is capableof giving, yields better than 70 or 75% under ordinary operatingconditions. This line is not drawn on a basis of actual chemicaldifferences, but constitutes one of practical utilization. It should beunderstood-also that when a diluent is tion. In the present invention,any zeolite" spoken of a catalytically effective component, what ismeant is that adiluent when incor orated or associated with a zeolite iscapa 1e of giving satisfactory yields in a contact sulphuric acid'process. In many cases, the diluent used alone would not bean efiectivecatalyst within the meaning of the term as used in the presentspecificaor base exchange body which is not itself an effective catalystmay be used. In addition to the ordinary zeolites which are baseexchangin polysilicates, of two kinds of reacting components, there arealso included base exchanging olysilicates which are the reactionprofucts of more than two kinds of components, and which for simplicitywill behbreinafter re ferred to as multi-component zeolites, and baseexchange bodies whichrdo not contain silicon and,which will be referredto as nonsilicious base exchange bodies. The words -llbase exchange bodywill be used generally to cover these three classes. It should beunderstood that I 'do'not claim herein the.

multi-component zeolites and non-silicious base exchange bodies as newchemical compounds, this constituting the subject-matter of myco-pending applications, Serial No. 142,783, filed October 19, 1926, andSerial No. 171,727, filed February 28, 1927.

The base exchange body containing a catalytically effective diluent mayor may not constitute a single base exchange bod and a mixture of aplurality of base exc iange bodies belonging to one or more of the aboveindicated classes may be used. A. plurality of catalytically effectiveelements may also be incorporated with or without further diluents,which may be inert or which may act as activators, promoters orstabilizers of the catalyst components themselves;

The base exchange bodies can be prepared the reaction products .less asan adhesive.

in a wet form orby fusion methods as is well known to the art and as hasbeen de scribed in my co-pending applications, above referred to, andalso in the co-pending joint applications of A. O. Jaeger and J. A.Bertsch, Serial No. 100.116, filed April 6, 1926, Serial No. 95, 771,filed March 18, 1926, and Serial No. 91,229, filed February 27, 1926.

In every case, however, the base excha-n e.

bodies retain their advantageous high a.

sorptive and adsorptive characteristics, their mechanical strength, andhoneycomb-like,

employed in the case of catal tically effective diluents which are inclued under the present invention.

l. -The catalytically effiective diluents may be mixed with one or otherof liquid com,- ponents of the base exchange body to be ormed when thelatter is prepared by wet methods.

2. The catalytically active components can be precipitated orincorporated by impregnation or by any other manner into diluent bodieswhich are themselves not catalytically effective and which may be inert,activating, stabilizing or promote stabilization. Thesediluent bodiesare then incorporated into the base exchange body by any of the'othersuitable incorporation methods.

'3. The catalytically effective diluents are to be mixed with the baseexchange bodies when the latter are in the form of gels by kneading orstirring, in which case'the base exchanging gel may be considered moreor The homogeneity and uniformity of the distribution of thecatalytically efl'ective'clements is, of course, not as great. by thismethod as by methods 1 and 2, but for many purposes extreme uniformityis not necessary and may even be undesirable.

4. The catalytically effective components- :may be formed during theformation of the base exchange body in the same by mixing suitablecomponents with the components of the base exchange body so that thereaction, whereby the latter is formed, will also form the catalyticallyeffective diluent particles. The addition of protective colloids may bedesirable to prevent coa ulation of the diluent particles before the aseexchange body has become sufficiently set.

5. A somewhatsimilar method to 4 can be used in which part of the baseexchange body components react with the eatalytically effectivecomponents during base exchange body formation to produce the necessarycatalytically effective particles. Thus, for example, salts of vanadicacid can be introduced into a base exchange body by using an excess ofa. metal salt component during base exchange body formation to reactwith and form salts of vanadic acid.

6. Ready prepared base exchange bodies,

diluted or undiluted artificial or natural can beimpregnated with trueor colloidal solutions of the eatalytically effective components, theproduct thereafter being dried.

7. A ready prepared base exchange body, diluted or undiluted, may beimpregnated with a plurality of solutions which react therein toprecipitate the catalytically effective diluent.

8. Soluble, catalytically effective compounds can be added to thecomponents forming a, base exchange body which after formation retainsthe catalytically effective components in solution and is dried withoutwashing or is treated to precipitate the cat alytically effectivecompounds.

9. The natural or artificial base exchange bodies, diluted or undiluted,may be impregnated with solutions of catalytically effective compoundswhich are then precipitated by treatment with gases.

The above nine methods briefly recapitulate the general methods ofincorporating diluents into base exchange bodies. Of course, other meansmay be used and particularly a combination of two or more of the abovedescribed methods may be utilized and is frequently desirable. IngeneraL-zmy of the methods described in the co-pending application of Jaeger & Bertsch, Serial No. 95,771, filed March 18, 1926, can beemployed mu-- tatis mutandis, to introduce catalytically ef-' fectivediluents into base exchange bodies or mixtures of base exchange bodies.

The diluted base exchange bodies of the present invention may be furthertreated with salt solutions to introduce bases in exchangeable form,which bases may themselves have some catalytic activity, but which areusually of an activating or stabilizing nature or promote thestabilization of cat-- alysts. The base exchange body after formationmay also be treated with compounds containing acid radicals which arenot in themselves effective catalysts to form the so caged salt-likebodies with the base exchange bo y.

The base exchange bodies may be incorporated with'diluents by a finemechanical mixture, followed by forming into workable fragments by meansof a suitable adhesive. Ingeneral, however, this method of preparationdoes not produce a uniformly line and homogeneous subdivision of thecatalytically effective component with the base exchangebody, andcontact masses so produced are generally not as efiicient as thoseprepared by the wet methods referred to hereinabove. Nevertheless,howeveC, it is possible to make contact masses by this method and theyare included in the scope of the present invention. It should be alsounderstood that many of'the nine methods d .=scribod above in connectionwith base exchange bodies prepared by wet processes can also be utilizedin connection with the well known fusion processes for the production ofbase exchange bodies. The applicability will be obvious to the skilledchemist.

In general, is should be understood that contact masses of the presentinvention contain at least two kinds of components, namely, acatalytically effective component physically combined with a baseexchanging component which is not itself an effective catalyst. Thecontact masses, may, however, in addition to these two components,contain others, such as diluents of a porous .or other nature, chemicalcompounds admixed mechanically or united by physical means with thecontact mass, or produced by treatment thereof, which act as stabilizersand tend to smooth out undue violence of reaction. Notably, compoundswhich are salts of alkali-forming and similar metals, such as earthmetals, act as stabilizers. Certain other compounds, notably compoundsof many amphoteric metals and compounds which contain silicic acid,appear to enhance and amplify thestabilizin effect of the salts of thebasic metals and tliese compounds I have termed stabilizer promoters.Obviously, of course, in many cases,-a single component mayperform morethan one function. Thus, a zeolite may act as a base exchange body withits desirable,zphysica'l structure and it may, by virtue of the ,alkalicontained therein, act also as astabilizeniand, by virtue of thesi-licicacid present, act as a stabilizer I promoter. All such products,when used for the catalytic oxidation of sulphur dioxide, are includedwithin the present invention.

Among the elements from which catalytically effective components canbe'prepared are the metal elements of the 5th and 6th groups of theperiodic system such as vanadium, molybdenum, tungsten, uranium,chromium, manganese, "arsenic, antimony, tantalum, niobium and bismuth.In addition to these particularly catalytic elements, other metalelements such as manganese, beryllium, aluminum, titanium, iron, copperzirconium, zinc, lead, silver, cerium, nickel, cobalt, boron and therare earths may be associated and nent.

enhance the activity of the catalyst in man eases. The-most importantcata ytically e fective components are those whlch contain platinum andvanadium, such as, for ex-- eatalytically effective component will notex-,

ceed 5 or 10% of the total weight of the contact mass. .The additionaldiluent bodies with which the catalytically effective components can beassociated in the base exchange body are not limited and any suitablediluents can be used. I have found that diluents. which have highadsorptive and absorptive powers act as activators by reason of theirphysical characteristics and are very desirable. The particle size ofthe diluents may vary within widelimits, but I have found thatilfinelydivided diluents, particularly tliose, sless than 60 microns areadvantageous as they produce a morehomogeneous product. Among thediluents may be mentioned kieselguhrs of all kinds, with orwithoutpreliminary treatments, fullers earth, talc, pulverized catalyticallyineffective'base exchange bodies of natural or artificial origin, rocks,stones, tufi's, trass, lava, etc.,' of volcanic or eruptive origin,green-sand, slag wool, pulverized slag, cement, silica gel, quartzfilter stones,

pulverized earthenware, pulverized natural or artificial silicates,glasspowder, graphite, pulverized mineralsrich in quartz, pumice meal,metal powders, and metal alloy owders, pulverized un-glazed porcelain,an the like. In general, any of the diluents described in theapplication of Jaeger and Bertsch, Serial No. 95,771, filed March 18,1926, may be used singly or in mixtures.

It will be readily seen that the number of possible catalysts isenormous and many of them, particularly where the proportions of thecatalytically effective components and associated compounds are properlychosen,

are of extraordinary effectiveness. The physical characteristics of theproducts, of course, will vary in accordance with the conditions underwhich they are prepared and any of the general methods and conditionsdescribed in the applications mentioned above of J aeger & Bertsch,Serial No. 100,- 116, filed April 6, 1926,.Serial No. 95,771,

filed March 18, 1926, and Serial No. 91,229, filed February 27, 1926,and my co-pending applications, Serial No. 142,783, filed October 19,1926, and Serial No. 171,727, filed February 28 1927, will be usedandare illustrated in the examples.

In general, the contact masses to be used for the oxidation of sulphurdioxide should be given preliminary treatment with air or SO containinggases or both. The catalytic reaction brings about certain changes inthe chemical composition of the base exchange bodies, without, however,affecting their physical structure. Therefore, I do not wish to beunderstood as maintaining that the catalysts remain unchanged during=the reaction and they are defined as of the time of preparation as iscustomary in catalytic chemistry. These secondary transformations aresometimes relatively ineffective; in other cases, they may be importantin controlling the catalytic efficiency of the mass. Thus, for example,durirg the contact sulphuric acid" process, the S0 produced will usuallyreact with thebase exchange bodies, present and will react with thealkali present, forming certain alkali bisulphates or-bisulphates of theexchangeable bases which may be present. These compoundsfor the mostpart are stabilizers so that in many cases the reaction itself producesin the catalyst the necessary stabilizer. Where a greater amount ofstabilizer is required, it maybe added in the form of the desired saltor the basic oxide may be added and further amounts of stabilizerproduced by the reactioii itself.

, The invention will be lllustrated in detail in the following examples,which are to be Q understood merely as illustrations of certain methodsof carryin out the principles of the invention, WhiChJS innosenselimited to the exact details therein set forth. 'It should.

be understood, however, that in many of the examples, specificfeatures'of great value are described and such features are included inthe narrow and preferred embodiments of the invention, although they donot limit its broad scope.

Example 1.

12 parts of V 0 are, dissolved by means of 12.4 parts of KOH in 200-250parts of water, and 80 parts of-infusorial earth are stirred in. Thesuspension-obtained is then treated with .12 parts of ferric chloridedissolved in to 150 parts of water, the temperature being maintainedatabout 40.to 50 C. After all the ferric chloride has been added, thereaction mixture is made neutral" to litmus by the gradual addition of2N sulphuric acid. A mixture of ferric vanadate and infusorial earth isobtained, which is separated from the mother liquor by filtration, andthen washed with 200 is added with vigorous stirring in order to obtaina uniform distribution. 60 parts of aluminum sulphate with 18 mols ofwater are dissolved in 200 part-s of water and sufficient N/lO potassiumhydroxide solution is added to dissolve up the aluminum oxide which isat first precipitated, forming a potassium aluminate solution. Thealuminate solution is then stirred into the suspension and the mixtureheated up to about 60 C. A gelatinous precipitate is obtained almost atonce, and is increased by the gradual addition of 2N sulphuric acid.Care should be taken, however, that a weak alkalinity toph-enolphthalein is maintained. The stirring is continued for an hour,the mixture being'gradually permitted to cool down to room temperature.The gelatinous precipitate obtained is pressed and Washed with 200 partsof water in small portions. The yellow filter cake is then dried atabout 80 Q, and broken--into fragments of suitable size.

Two to four volumes of the contact mass thus produced are placed in acontact sulphuric acid converter and a thousand to two thousand volumesof 7 9 per cent burner gases are passed over the catalyst per hour attemperatures of about 450 to 500 C. A yieldot 96 to 98.5% of thetheoretical is obtained. The catalyst is very resistant to hightemperatures.

Instead of using iron vanadate as a diluent in the zeolite formed othercatalytically active of vanadium, such as the vanadites or trivalentvanadium salts, may be substituted.

Equivalent amounts of salts oftetravalent and pentavalent vanadium, suchas for example, the nickel, cobalt, manganese, uranium, copper,aluminum, titanium, silver, barium or calcium salts, may be used, eithersingly or in admixture, as catalytically active diluents in the zeolite.These catalysts are capable of giving yields up to 98.5% of the theoryunder reaction conditions as outlined above.

ilmenite, bauxite, chromium oxide, manganese dioxide, copper dioxide,materials rich in silicic acid such as roughened fragments of quartz,flint, pumice fragments, broken quartz filter stones; or artificialcarriers rich in silicic acid, such as for example carriers preparedfrom kieselguhr and waterglass, kieselguhr andpotassium aluminate,zeolites, kieselguhr and alkalics, or alkali salts and the like. Metalsand metal alloys may also be used, such as for example aluminumgranules, roughened fragments of ferro-vanadium, term-molybdenum,ferrosilicon, silicon-ferro-manganese, siliconaluminum-ferro-manganese,ferro-titanium, term-tungsten, and the like. These contact masses can beprepared by causing the waterglass-infusorial earth-iron vanadatesuspension to. adhere to the carriers, and then forming the zeolite bythe addition of the aluminate solution, or by spraying with an aluminumsulphate solution, in which case a zeolite is produced which is of thealuminum double silicate type.

It is sometimes advantageous in preparing contact masses to introducediluent bodies, which can then be removed by washing or by calcining.Thus for example, 5 to 10% of flour, starch or sugar can be incorporatedinto the catalyst during the formation of the zeolite and later removedby washing or calcining, leaving still further pores in the contactmasses, and thereby increasing its effectiveness as a catalyst.

The salts of tetra'valent and pentavalent vanadium can also beSubstituted partially by salts of the oxygen containing acids of themetals of the fifth and sixth groups of the periodic system, as forexample, tantalum, tungsten, molybdenum and chromium. Where, however,highly effective catalysts are desired, the substitution of these othercatalytic components should not exceed'10 to 15%.-

It should be understood in general that the catalysts of the followingexamples can also be coated onto the massive carrier fragments, as hasbeen described in detail in connection with the catalysts of the presentexample.

Ewample 18.2 parts of V 0 are dissolved in the least quantity of normalsodium hydroxide solution, in order to 'form the sodium metavanadate. 34parts of silver nitrate dissolved in 250 parts of water are then addedwith vigorous stirring, precipitating out the yellow silver vanadate.The precipitate is permitted to settle, decanted several times withwater to remove the sodium nitrate formed, and then 500 parts of a 33 B.potassium waterglass solution diluted with eight to ten volumes of waterare added. 42.5 parts of aluminum-- oxide are dissolved in 2N potassiumhydroxide to loo form potassium aluminate, and this solution is thenpoured into the silver vanadatewaterglass-suspen'sion with vigorousagitation, the temperature being maintained at about 4050 C. In a shorttime considerable amounts of aluminum zeolites are formed, and theyields are greatly increased by a cautious addition of N/2 sulphuricacid, care being taken that a weakly alkaline reaction tophenolphthalein remains after the last addition of sulphuric acid. Thezeolite containing silver-Vanadate in a fine state of division is thenpressed in the usual manner, dried at temperatures up to 80, andhydrated by causing four to five volumes of water to trickle over it.The hydration causes the product to break up into small fragments, whichare then treated with a 5% calcium chloride or strontiumchloridewaterglass-silver vanadate suspension, and

then the aluminum sulphate solution is added with vigorous agitation,the reaction mixture solidifying to a thick gel of a so calledmulti-component zeolite, in which silver-vanadate is present as aca'talytically effective diluent.

Aluminum oxide, which behaves as an am- -photeric metal oxide in thiscomposite catalyst, can also be substituted partly or wholly by otheramphoteric metal oxides, especially beryllium oxide, cadmium oxide andchromium oxide. These oxides maybe intro- .duced partly orwholly'eit-her in the form of the alkaline metal metallates or intheform of metal salts. Instead of silver vanadate, other vanadates of theheavy metals can be used as catalytically effective diluents. Similarsalts of tetravalent vanadium are also effective. In" general, suchcontact masses which contain about 10 to 15% of catalytically effectivediluents are excellent contact masses for catalytic oxidation of sulphurdioxide. 7% burner gases freed from dust, but containing the-so-calledcatalyst poisons are passed over these contact masses at 450-550 (1, andin a short time an excellent contact sulphuric acid process begins,giving yields up to 96% of the theory.

Ewamp le 3.

tion containing 15 parts of 90% sodium ing C. A ferric chloride solutioncontaining 9 arts of ferric-chloride in 150 parts of water 1s then addedwith vigorous agitation, and after all the ferric chloride has beenadded the reaction mixture is rendered neutral to litmus by means of 2Nsulphuric acid, and permitted to cool down to' room temperature. Adiluted iron vanadate precipitates out and is sucked and washed.

200 parts of 33 B. waterglass are diluted with 400600 parts of water,and the iron vanadate filter cake suspended therein. 26.4 parts offerric sulphate with 9 mols of water are dissolved in 250 parts ofwater, or instead of the ferric sulphate solution a solution containing29.3 parts of manganese sulphate with 4 mols of water can be prepared,or an equivalent "mixture of ferric and manganese sulphates may be used.The ferric sulphate solutionor manganese sulphate solution is thenintroduced intothe waterglass-iron-vanadate suspension with vigorousagitation, the whole mass soon solidifying to a yellow gel which showsan alkaline reaction to phenolphthalein. The

'gel is recovered from the mother liquor in the usual way b pressing anddrying at temperatures un er 100 C., and contains an iron zeolite inwhich both catalytically efli'ective and catalytically indifferent dilucuts are embedded.

The contact mass is broken into fragments and first blown with air, thetemperature gradually rising to 450 C. Thereupon the Ewample 4.

a A diluted aluminum zeolite is formed by introducing to 80 parts offinely ground silicatae rock, burnt pyrites or infusorial earth into 90to 100 parts of a 33 B. waterglass solution which has been diluted with300-500 parts of water, and which is then caused to react with apotassium alumina-te solution prepared by addin suflicient half normalpotassium hydroxidjs solution to an aluminum sulphate solution contain-55 parts of aluminumt sulphate with 18 mols of water in 200 parts ofwater until the aluminum hydroxide which at first precipitates is againdissolved in the form C. and increased yields obtained by gradualaddition of 2N sulphuric acid. The product is adiluted aluminum zeolite,which is not an eilective catalyst for the contact sulphuric acidprocess. Instead of the two-component aluminum zeolite, athree-component aluminum zeolite can be prepared, 1n which part of thealuminumis introduced in the form of an alkali metal aluminate and the.other part in the form of an aluminum salt.

An aluminum zeolite of the character of an aluminum double silicate canalso be prepared by causing an aluminum sulphate solution to react withthe waterglass solution, to which sufficient alkali has been added sothat when all of the aluminum sulphate has been introduced the mixturestill reacts alkaline to phenolphthalein.

Instead of the aluminum oxide component,- other amphoteric metal oxidesin the form of salts or metallates can be used, for exam-' ple, oxidesof beryllium, cadmium, zirconium, zinc and titanium, smgly or 1nmixtures. These amphoteric metal oxides may also be used in conjunctionwith aluminum.

The diluted zeolites are broken into fragments, impregnated at anelevated temperature with 12 parts of V 0 in the form of an ammoniumvanadate solution, and then impregnated with 7.12 parts of ferricchloride dissolved in 100150 parts of water. The product is again dried,and constitutes a zeolite impregnated with iron vanadatc. The zeolite iscalcined in order to remove the ammonium chloride formed, which resultsin a still further increase in the porosity of the product, and is thentreated with 7% burner gases, an excellent contact sulphuric processsoon setting in.

In a similar manner, other salts of vanadic acid can be used, such asfor example, copper vanadate, silver vanadate, manganese vanadate,titanium vanadate, cobalt vanadate or nickel vanadate, either alone or.

together with iron vanadate. Mixtures of these salts may of course alsobe used.

It is possible also to substitute part of the vanadates b thecorresponding tungstates. or molyb ates. Salts of tetravalent vanadiumacids may also be used.

Instead of forming the salts as described, V 0 can be introduced intozeolites by impregnation with ammonium or potassium vanadate solutions,followed by a treatment to remove the base, for example, by calcining inthe case of ammonium, or by treating with 7% burner gases. The V. ,O isembedded in the zeolite in a finely divided form. An equivalent amountof vanadyl sulphate may also. be used, and yields a highly effectivecontact mass when used under the ordinary operating conditions asdescribed in the foregoing examples.

Example 5.

A zeolite is prepared as described in Exponents being kneaded into thegel. After drying and treating in the usual manner,

excellent catalysts for the contact sulphuric acid process are obtained.

' ing sulphur trioxide or spraying with dilute sulphuric acid thenprecipitates the V 0 in a fine state of division in the zeolite.

Example 6.

400 parts of 33 B. waterglass are diluted with 6 to 8 volumes of water,and 497 parts of ferric sulphate containing 9 mols of water dissolved toform a 10% aqueous solution are added, producing on iron silicate whichdoes not show any base exchanging powers. Into this iron silicate eitherwet or after drying, iron vanadate is introduced either ready preparedor in the form of components which cause its formation in situ. The iron'vanadate may be prepared by dissolving 15 parts of V 0 in about 15parts of 90% sodium hydroxide and adding 15 parts of ferric sulphatewith 9 mols of water in the form of a 15% solution. 100 parts of 33 Be.waterglass are diluted With 6 to 7 volumes of water, and

case it Will not be necessary at a later point to add acids toneutralize the excess of alkali in the zeolite components. Thewaterglass suspension and the aluminate solution are poured together,and the zeolite precipitated either by means of normal sulphuric acid orif part of the aluminum is present in the form of aluminum sulphate athree component zeolite is formed. The aluminum can be partly or whollysubstituted by beryllium, cadmium or zirconium, singly or in mixtures.

The gel obtained is pressed in the usual manner, dried at temperaturesbelow 100 (3., broken into fragments and hydrated by permitting 400 to500 parts of water to trickle over it. After hydration the exchangeablealkali metal bases may be partly exchanged for iron, copper, nickel,chromium, calcium or strontium by digesting the hydrated zeolite with a5% solution of these metals. In the contact mass produced thecatalytically efiective component is the iron .the iron silicatecontaining iron vanadate vanadate impregnated into the iron silicate,and this may be substituted partly or wholly by other metal salts oftet'ravalent or pentavalent vanadium, such as for example thesilversalts or copper salts. The iron silicate maybe considered here asa stabilizer promoter, which promotes or tunes the stabilizing efie'ctof the zeolite.

Example '7. w

has been added thereaction mixture is neu-' tral to litmus. Theprecipitate is sucked and thoroughly Washed, and is stirred into 100parts of 33 B. waterglass, which has been diluted with four or fivevolumes of water. 55-60 arts of aluminum sulphate with 18 mols 0? waterare dissolved in 200 parts of water and then transformed into potassiumaluminate by means of N/2 potassium-hydroxide solution. 'The waterglasssuspen sion and potassium aluminate solutions are then poured togetherand sufiicient normal sulphuric acid or other acids such as hydrochloricacid is added, until a gel is precipitated as quantitatively aspossible. The mother liquor should show a strong alkaline reaction tolitmus. The product is worked up in the usual way, broken into fragmentsand constitutes a zeolite contact mass containing vanadyl-silicatediluted with celite. The contact mass is calcined with air at 400 0.,and when treated with 7-9% burner gases gives good yields of sulphurtrioxide at 430-480" C. I An excellent contact mass is also obtained bydrying the zeolite and coating it onto quartz or flint fragments bymeans of a little waterglass or alkali. The catalytic efiectivencssremains, and considerable amounts of material are saved.

E wample 8. i

55 parts of aluminum sulphate containing 18 mols of water are dissolvedin 300 parts of water, to which; is added a solution containing 17 partsof ferric sulphate with 9 mols of'water in 200 parts of water. An 8%sodium metavanadate solution is poured into the aluminum and ironsulphate solu tions until 16 parts of V 0 have been added. Vigorousagitation should be maintained, and a precipitate of iron-aluminumvanadate results, the precipitate in a very fine state of subdivision.120 parts of 33 B. waterglass diluted with 5 to 6 volumes of water aremixed with 60 to 80 parts of .diatomite brick refuse, and theiron-aluminum vanadate is then added, together with sufiiis in the formof a diluent, and the product is worked up in the usual manner bypressing, washing with 4004500 parts of water and drying under 100 C.The contact mass is broken into fragments, calcined, and when treatedwith 6-9% burner gases at 430 480 (1., gives excellent yields of sulphurtrioxide up to 98% of the theoretical,

In a similar manner, other salts of vanadic acid or salts of tungsticand molybdic acids,

for example, the silver, titanium, calcium,

copper, cobalt, nickel or manganese salts may be used, singly or inmixture. After hydrating, these contact masses may also be treated with5% silver-nitrated or copper nitrate, in order to introduce theseelements into the zeolite in exchangeable form.

Example .9.

Instead of carrying out the reaction as described in Example 8, apotassium metavanadate solution, containing 16 parts of treated asdescribed in Example 8 are excellent for the contact sulphuric acidprocess. Example 10 Natural or artificial zeolites, as for example,commercially obtainable, or zeolites which contain catalytically'inactive diluents which may be considered as stabilizer promoters, areimpregnated with an ammonium vanadate solution, or with an'ammoniacalsilver vanadate solution, and calcined or impregnated with calciumvanadate, lithium vanadate, caesium vanadate, rubidium vanadate, andthen sprayed with dilute suphuric acid or treated with gases containingsulphur trioxide forming V .0, in a finely divided state in the zeolitestructure. These products 'are excellent catalysts for contact weight.

Ewample 11.

10.2 parts of aluminum oxide are dissolved by means of 40 parts of 100%KOH in 300 parts of water. 80 parts of kieselguhr are then impregnatedwith an ammoniacal silver vanadate solution prepared from 18.2 parts ofV 0 and 34 parts of silver nitrate dissolved in 20% ammonia water. Afterim pregnation is complete the ammonia is removed by heating; Thekieselguhr-silver vanadate mixture is stirred into the potassiumaluminate solution, and then a solution containing 37 parts of ferricsulphate containing 9 mols of water in 250 parts of water is added withvigorous agitation, producing a non-silicious base exchange body, whichcontains a catalyticalljy efiective d1 went and also kieselguhr. .hethick precipitate formed is pressed, washed with about 200 parts ofwaterin small portions, then dried as usual under 100 C., broken intofragments and calcined. The contact mass so obtained is an excellentsulphuric acid catalyst.

Instead of silver 'vanadate, copper vana-' date, iron vanadate ormanganese vanadate can be used, or the vanadate salt can be produced inthe acid reaction component, namely, the iron sul hate solution, acorresponding amount 0 heavy metal salt, that is,

either iron sulphate, copper sulphate or silver nitrate being added toreact with 18.2 parts of V 0, which is added in the form of the alkalimetal metavanadate.

Emmple 12.

, parts of a 33 B. potassium waterglas's solution diluted with four tofive volumes of water are mixed with 60 arts of infusorial earth,- withvigorous stirring. 55.5 parts of aluminum sulphate containing 8 mols ofwater dissolved in 200 parts of water are treated with suflicient normalpotassium hydroxide solution until until all the aluminum is dissolvedas potassium aluminate. A i

2% chloro'platinic acid solution containing 5 arts of latinum is thentreated with a 3% ormalde yde solution, in order to preci itate theplatinum in colloidal form. he

waterglass andpotassium aluminate solution and colloidal platinumsolution are then poured together, and sufiicient normal sulphuric acidis added to precipitate the zeolite quantitatively. The product is thensucked and dried at temperatures below C., and constitutes azeolitecontaining platinum and. kieselguhr as diluents. When broken intofragments it is an excellent latun-v inum sulphuric acid catalyst, whenus derJthe usual working cohditions with 7% burner. asesat 400-450 C.The burner gases 0 course must be freed from compounds which act ascatalyst. poisons for platinum.

-What is claimed as new is-- 1. A contact sulphuric acid process whichcomprises assing gases containing sulphur dioxide an oxygen at,reactiontemperatures over a catalyst containing a catalytically ineffective baseexchange body hysically combined with a. catalytically e ective diluent.

2. A process according to claim 1, in

which the base exchange body and diluent are united in structure. U

3. A contact sulphuric acid process which comprises passing gasescontaming sulphur dioxide and oxygen at reaction temperatures over acatalyst comprising a catalytically ineffective base exchange body phsically associated to at least one catalytlca eflective diluent and atleast one'catalyticall y tive diluent. 4

4. A process according to claim 3, in which at least part of thecatalytica lly effective diluent component is impregnated into at leastpart of the catalytically inefiective diluent.

a 5. A process according to claim 1, in which exchangeable bases otherthan alkali metals are introduced intothe base exchange body by baseexchange.

6. A process according to claim 1, in which the catalyst contains astabilizer.

7. A process according to claim 1, in which the catalyst contains avstabilizer and a stabilizer promoter.

8. A process according to claim 3, in which a physically homogeneousdiluent is a stabilizer.

9. A process accordin to claim 3, in which both stabilizers and stailizer promoters are present in the diluent.

' 10. /A method accordin to claim 1, in which thebase exchange Eodycontains exchangeable bases which react with sulphur iSIiOXldG to formstabilizers.

11. A process according to claim 1, in which. the base exchange body is,a zeolite. 12. The process accordin to claim 1, in which the baseexchange y does not contain silicon. Y

. 13. A contact sulphuric acid rocess which comprises assing gasescontaining sulphur. dioxide an oxygenat reaction temperatures over acatalyst containing a catalytically ineffective base exchange bodyhaving physically associated therewith a'rcatalytically effectivediluent, at least part of the catalytically efi'ective component thereofbeing a compound of vanadlum.

14. A process according to claim 13, in which the vanadium compounds areassociat-' ed with other catalytically efiective components notexceeding 15% by molecular equivat leastpart of the catalyticallyinefiective dioxide and oxygen at reaction temperatures.

over a catalyst comprising a catalytically inefi ective base exchangebody physicall associated with catalytica lly effective di uentcontaining at least one vanadium salt.

16. A process according to claim 15, in

non-base exchanging vanadyl silicate.

17 A contact sulphuric acid process which comprises passing gasescontaining sulphurdioxide and oxygen at reaction temperatures over acatalyst comprising a base exchange body having catalytic activity butbeing catalytically inefi'ective associated with a catalyticallyefiective diluent.

18. A process according to claim 17 in which the base exchange bodycontains a heavy metal in non-exchangeable form.

19. A process according to claim 1, in which the catalytically effective,component of the diluent has been formed insitu.

effective base exchange bodyhysically as-.

sociated with a catalytically e ective diluent,

the catalyticaly effective component of which which at least one of thevanadium salts is a has been formedin situ from a compound containingremovable constituents and which constituents have been removed bysubseuent treatment under conditions toincreasc t o porosity of theproduct.

21. The process according to claim I, in

which the diluted base exchange body is coated onto massive carrierfragments.

22. A process according to claim 1, in which the catalytically effectivecomponents are not platinum components and the reac- "tion gases containplatinum catalyst poisons.

Signed at Pitts urgh, Pennsy 8th day of March, 1927.

'. ALPHON S O. JAEGER.

vania, this

